improvement(Windows): Support window capture protection #1424

Author: AChep

common/src/commonMain/kotlin/com/artemchep/keyguard/feature/home/settings/component/SettingScreenshots.kt

@@ -78,6 +78,7 @@ fun settingScreenshotsProvider(
     SettingIi(
         platformClasses = listOf(
             Platform.Mobile::class,
+            Platform.Desktop.Windows::class,
         ),
         search = SettingIi.Search(
             group = "conceal",

common/src/desktopMain/kotlin/com/artemchep/keyguard/ui/WindowScreenshotProtectionEffect.kt

@@ -0,0 +1,60 @@
+package com.artemchep.keyguard.ui
+
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import arrow.core.throwIfFatal
+import com.artemchep.jna.windows.setWindowExcludedFromCapture
+import com.artemchep.keyguard.common.model.AllowScreenshots
+import com.artemchep.keyguard.common.usecase.GetAllowScreenshots
+import com.artemchep.keyguard.platform.CurrentPlatform
+import com.artemchep.keyguard.platform.Platform
+import com.artemchep.keyguard.platform.recordException
+import com.artemchep.keyguard.platform.recordLog
+import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.flow.distinctUntilChanged
+import kotlinx.coroutines.flow.onEach
+import org.kodein.di.compose.rememberInstance
+
+@Composable
+fun WindowScreenshotProtectionEffect() {
+    if (CurrentPlatform !is Platform.Desktop.Windows) {
+        return
+    }
+
+    val window = LocalComposeWindow.current
+    val windowHandle = window.windowHandle
+    val getAllowScreenshots by rememberInstance<GetAllowScreenshots>()
+    LaunchedEffect(
+        getAllowScreenshots,
+        windowHandle,
+    ) {
+        getAllowScreenshots()
+            .distinctUntilChanged()
+            .onEach { allowScreenshots ->
+                val excluded = allowScreenshots < AllowScreenshots.LIMITED
+                applyWindowScreenshotProtection(
+                    windowHandle = windowHandle,
+                    excluded = excluded,
+                )
+            }
+            .collect()
+    }
+}
+
+private fun applyWindowScreenshotProtection(
+    windowHandle: Long,
+    excluded: Boolean,
+) {
+    try {
+        val success = setWindowExcludedFromCapture(
+            windowHandle = windowHandle,
+            excluded = excluded,
+        )
+        if (!success) {
+            recordLog("Failed to update Windows screenshot protection.")
+        }
+    } catch (e: Throwable) {
+        e.throwIfFatal()
+        recordException(e)
+    }
+}

desktopApp/src/jvmMain/kotlin/com/artemchep/keyguard/Main.kt

@@ -96,6 +96,7 @@ import com.artemchep.keyguard.platform.util.isRelease
 import com.artemchep.keyguard.res.Res
 import com.artemchep.keyguard.res.*
 import com.artemchep.keyguard.ui.LocalComposeWindow
+import com.artemchep.keyguard.ui.WindowScreenshotProtectionEffect
 import com.artemchep.keyguard.ui.surface.LocalBackgroundManager
 import com.artemchep.keyguard.ui.surface.LocalSurfaceColor
 import com.artemchep.keyguard.ui.theme.GlobalExpressive
@@ -597,6 +598,8 @@ internal fun FrameWindowScope.KeyguardWindowEssentials(
         LocalComposeWindow provides this.window,
         LocalWindowId provides windowId,
     ) {
+        WindowScreenshotProtectionEffect()
+
         LaunchLifecycleProviderEffect(
             processLifecycleProvider = processLifecycleProvider,
         )

desktopLibJvm/src/jvmMain/kotlin/com/artemchep/jna/windows/WindowDisplayAffinity.kt

@@ -0,0 +1,44 @@
+package com.artemchep.jna.windows
+
+import com.sun.jna.Native
+import com.sun.jna.Pointer
+import com.sun.jna.win32.StdCallLibrary
+
+private const val WDA_NONE = 0x00000000
+private const val WDA_EXCLUDEFROMCAPTURE = 0x00000011
+
+public fun setWindowExcludedFromCapture(
+    windowHandle: Long,
+    excluded: Boolean,
+): Boolean {
+    if (windowHandle == 0L) {
+        return false
+    }
+
+    val affinity = if (excluded) {
+        WDA_EXCLUDEFROMCAPTURE
+    } else {
+        WDA_NONE
+    }
+    return User32.INSTANCE.SetWindowDisplayAffinity(
+        Pointer.createConstant(windowHandle),
+        affinity,
+    )
+}
+
+@Suppress("FunctionName")
+private interface User32 : StdCallLibrary {
+    companion object {
+        val INSTANCE: User32 by lazy {
+            Native.load(
+                "user32",
+                User32::class.java,
+            ) as User32
+        }
+    }
+
+    fun SetWindowDisplayAffinity(
+        hWnd: Pointer,
+        dwAffinity: Int,
+    ): Boolean
+}